Instrument for optically measuring distances.



PATENTED MAR. 10, 1908.

H. JACOB. INSTRUMENT FOR OPTIGALLY MEASURING DISTANCES.

APPLIOATION FILED JULY 16, 1907.

UNITED STATES PATENT OFFICE HEINRICH JACOB, OF STEGLITZ, NEAR BEBLFN,GERMANY, ASSIGNOR TO THE FIRM OF OP'I'ISCHE ANSTALT C. P. GOERZAKTIENGESELLSCHAFT, OF FRI-EDENAU, NEAR BERLIN,

eEnManY.

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Patented March 10, 1908.

To all whom it may concern:

Be it known that I, HEINRICH Jason, a citizen of the German Empire, andresident of Steglitz, near Berlin, Germany, engineer, have inventedcertain new and useful Improvements in Instruments for OpticallyMeasuring Distances, of which the following is a specification.

My present invention relates to an optical distance-measurer provided atthe end points of a base of the instrument with two reflectors or prismsthe images of which are observed through a single ocular, there beingarranged in front of the ocular an image-uniting body consisting ofcrossed prisms or re-- flectors. In distance-measurers of this kind thedetermination of the distance of a certain object viewed through theinstrument is effected by producing an image with the aid of each ofthetwo reflectors at the end points of the base, the two pictures beingbrought into the field of view of the ocular, each by an element of theuniting body provided so that the distance can be ascertained from theadjustment of the instrument.

The reliability of the indicatinns. of. the instrument is dependent uponthe separate im. ages being united to a complete picture or singlepicture with complete sharpness. In practiceit is, however, diflicult.toascertain at what moment the outlines of part pictures come exactlytogether so that a uniform sin gle picture is produced, and it is alsodithcult to cause the double pictures to exactly register.

According to the present invention the sharp adjustment of theinstrument is facilitated by a special arrangement of the imageunitingbody whereby the observer is enabled to combine the adj ustment'foruniting part pictures'with an adjustment for making separate picturesregister. For this purpose the image-uniting body consisting of crossedprisms or reflectors is arranged between the objectives and the'ocularof the instrument at such a distance' from the common imageplane of theobjectives and the ocularthat etween two separated half-pictureslthereis,

a central zone with double images, which la..t,- ter coincide when theinstrument is adjusted with regard to a certain object and form the halfor part images a single complete image of the object with regard towhich the instrument is adjusted. I

The invention is illustrated in the annexed drawing in which: Figure 1is adiagrammatic representation of an instrument constructed accordingto the invention. Fig. 2 .a front view of the image-unitingbody,seenfrom the ocular side, while Figs. 3, 4 and 5 show the for'ms of theimages appearing in the f field of view before'adjustment, withdifferent arrangements of the image-uniting body relatively to theocular image-plane of the instrument, and Figs. 6, 7' and 8 showthecorresponding complete and single pictures appearing in the field ofview when sharp adjustment is obtained.

In the form of construction of the instru ment shown, there are arranged.at theend points of a base, prisms 1 and 2'which reflect I the raysentering: .them towards the objec' tives 3, 4 from which they ass totheimageuniting body 5, which int c example shown consists of the twocrossed prisms 6 and]. The ocular of the instrument is marked .8. Thecommon imagelane of the objectives 3, 4 and ocular 8 is in 'cated'at 9.It can be seen that the image-uniting body 5 is outside the image-plane9. Owing to the fact that the separating edge 10 of the prisms6 and? ofthe image-uniting body is outside the imageplane 9 it results that thelight rays after passing the prisms 6 and 7 cross each otheruninterruptedly so that the Zone in which this crossing of the lightrays takes place, there arev produced double pictures of the objectsimaged, while outside this zone only single part pictures are observed.The character of the image appearing in the field of view of theinstrument is therefore that illustrated in Fig. 5. If on the other handthe uniting body is so arranged that the sepa rating edge lOcoincideswith the image-plane 9 the image produced would lack the cengal doubleimage zone, and the picture would have the character of the formshownxin Fig.

3. If on the other handthe distance .of thebody 5 from" the image-planeof the instru ment were so selected that therays passing through theprisms 0t the-.p'icture-uniting bodies could cross eachiothjerwithouthindrance for the entire extent'of'the field-of view, the image producedwould have the character of a double image within the entire field ofview, as shown in Fig. 4. It will, however,

be seen that as was moreover mentioned in; the introduction of thisspecification, the

' and of the two single images of the doub e image shown'in Fig. 4, ismore difficult o "shownin Fig. 3 is are images of small uniting of twopart images, as shown in efiect with perfectly sharp limiting edges thanthe uniting of images consisting of three elements as shown in Fig. 5."I I The};"-Cl-ifliculty of uniting art images as. 1particular y greatif they .:ing to Fig. 4, whereas inversely with objects with .which itis 'difiicnlt to observe cpincidence vof double images, the unitin to asingle image can be easily effected with the part images available. Theuniting of the two images can'be efiected in known manner by ad ustingone or more prisms or one or both objectives or by special additionaland adjustable parts included into the path of the rays. I have disensed with the illustration of such special a justing means on thedrawing because such means are generally known and do not'forni part ofmy invention.

Having now particularly described and as-- certained the nature of mysaid invention and in what manner the same is to be performed, I declarethat what I claimis 1. In an optical distance measuring instrumentcomprising two objectives arranged at eight, for example points ,7

a distance from each other, each 006 erating with a prism, said prismsarranged ikewise at a distance from each other, an image-uniting bodybetween said two objectives and cooperating prisms and an ocular infront of said image-uniting body adapted to receive the rays coming fromsaid image-uniting body'and having an image-plane coinciding with theimage-plane of the said two objectives, the image-uniting body beingsituated at such a distance from the common imageplane. of theobjectives and ocular that between two separated half pictures there isproduced a central zone wit 1 double images, which latter coincide onadjustment of the instrument for a given object and form with the halfor part images a single full image of the object for which theadjustment is made.

2. In an optical distance measuring instrument comprising two objectivesarranged at a distance from each other, each 006 erating with a prism,said prisms arranged ikewise at a distance from each other, animage-uniting body provided with two reflecting surfaces forming anangle with each other, and being adjust-able with relation to eachother, said image-uniting body being situated between said twoobjectives and cooperating prisms and an ocular in front of saidimage-uniting body adapted 'to receive the rays coming.

from said image-uniting body and having an 1mage-plane coinciding withthe 1mage-p ane of the said two objectives, the image-uniting body beingsituated at such a distance from the common image-plaiie of theobjectives and ocular that between .two separated half pictures there isproduced a central zone with 7 double imageswhich latter coincide onadjustment of the instrument for a given object andform with the half orpart images a single full image of the object for which the adjustmentis made.'

In' testimony whereof I have signed this specification in the presenceof two subscribing witnesses.

I HEINRICH JACOB. \Vitnesses HENRY HAsPER, WoLDEnAR HAUPT.

